It is known to provide instruments which measure a breathing parameter of a user's breath, and which displays the result of the measurement for a user, sports scientist or doctor to review, for example.
In particular, devices are known for use in calorimetry, to study the energy of metabolism in humans and animals. Calorimetry is used, for example, for diagnosis of metabolic disorders and for calculating nutritional requirements of a subject. A useful calorimetric measure for nutritional and sports scientists when assessing the health and fitness of a subject is the volume of oxygen consumed at rest, and during or after physical exertion.
Indirect calorimetry often involves measuring the amount of carbon dioxide exhaled by a subject, which can in turn be used to calculate the oxygen consumption of a subject.
The measurement of the volume of oxygen consumed and/or the amount of carbon dioxide exhaled by a subjected are normally measured as a single reading, at rest, during or after physical exertion. Multiple measurements may be taken and plotted on a chart to indicate changes in oxygen and/or carbon dioxide measured over a period of time.
One problem with measuring parameters of breathing states, such as volume of oxygen consumed at rest and/or during or after physical exertion, is that the devices used to monitor the breathing parameter lead the user to “force” a breath, due to having to exhale and inhale through a breathing tube attached to the device. Thus the subject does not always breathe normally, and forces a breath from their lungs, or into their lungs as an instinctive reaction. The measurement of forced breaths does not give an accurate indication of the breathing parameter measured, as the breath will generally have a greater volume, speed, oxygen and/or carbon dioxide content or, if multiple breaths are measured, have irregular time intervals between breaths, or a lower or higher number of breaths in a predetermined time period than would be measured during normal breathing. It would be advantageous to provide a breath monitoring device which allows a user to determine whether a monitored breathing state is a “normal” breath or a “forced” breath.
Furthermore, with known devices for monitoring breath parameters, it is not generally possible to determine whether or not, during subsequent use of the devices, whether the same user is breathing into the device during each monitoring session. Thus, it would be advantageous to provide a device which would monitor and determine whether or not the same user is using the monitoring device on subsequent uses, after detecting and storing breath parameters of a specified user.
It is therefore an aim of preferred objects of the present invention to overcome or mitigate at least one of the problems of the prior art, whether expressly described hereinabove or not.